--- hw/xfree86/ddc/interpret_edid.c~	2013-10-03 07:25:56.000000000 +0100
+++ hw/xfree86/ddc/interpret_edid.c	2013-10-03 07:48:55.168972224 +0100
@@ -144,6 +144,15 @@
 
         xf86ForEachDetailedBlock(m, handle_detailed_hvsize, &p);
 
+        if ((p.real_hsize != m->features.hsize ) ||
+                (p.real_vsize != m->features.vsize)) {
+            xf86Msg(X_INFO, "Inconsistency in detected Display Size:\n");
+            xf86Msg(X_INFO, "Monitor features physical dimensions %dx%d mm\n",
+                m->features.hsize, m->features.vsize);
+            xf86Msg(X_INFO, "Detailed timings physical dimensions %dx%d mm\n",
+                p.real_hsize, p.real_vsize);
+        }
+
         if (!p.real_hsize || !p.real_vsize) {
             m->features.hsize = m->features.vsize = 0;
         }
--- hw/xfree86/modes/xf86Crtc.c.orig	2013-11-01 16:59:03.904169898 +0000
+++ hw/xfree86/modes/xf86Crtc.c	2013-11-01 17:06:28.387359579 +0000
@@ -3052,8 +3052,15 @@
              (det_mon->section.d_timings.v_size * 12)) &&
             ((det_mon->section.d_timings.v_size * 5) <
              (det_mon->section.d_timings.h_size * 12))) {
-            p->output->mm_width = det_mon->section.d_timings.h_size;
-            p->output->mm_height = det_mon->section.d_timings.v_size;
+            if (!(p->output->conf_monitor &&
+                (p->output->conf_monitor->mon_width > 0 &&
+                    p->output->conf_monitor->mon_height > 0))) {
+                /*
+                 * Do not update size if user configured DisplaySize
+                 */
+                p->output->mm_width = det_mon->section.d_timings.h_size;
+                p->output->mm_height = det_mon->section.d_timings.v_size;
+            }
             p->ret = TRUE;
         } else
             xf86DrvMsg(p->output->scrn->scrnIndex, X_WARNING,
@@ -3109,6 +3116,15 @@
     xf86OutputSetEDIDProperty(output, edid_mon ? edid_mon->rawData : NULL,
                               size);
 #endif
+    if (output->conf_monitor &&
+            (output->conf_monitor->mon_width > 0 &&
+                output->conf_monitor->mon_height > 0)) {
+            /*
+             * Prefer user configured DisplaySize
+             */
+            output->mm_width = output->conf_monitor->mon_width;
+            output->mm_height = output->conf_monitor->mon_height;
+    }
 
     if (edid_mon) {